(a) Field of the Invention
The present invention relates generally to an electromagnetic power divider/combiner and, more particularly, to a power divider/combiner having a movable slow-wave structure disposed in a portion of the cylindrical waveguide.
(b) Description of Related Art
A vertically oriented electromagnetic signal can be described as having two orthogonal components: a first component oriented at +45 degrees relative to the vertical and a second component oriented at -45 degrees relative to the vertical. Similarly, a horizontally oriented electromagnetic signal can be described as having two orthogonal components: a first component oriented at +45 degrees relative to the vertical and a second component oriented at +135 degrees relative to the vertical. The differential phase differences between the vertical and horizontal orientations (180 degrees) form the basis for the operation of a variable power divider/combiner (VPD/C). The orthogonal components of the two orientations can be manipulated using the VPD/C to create power splits at the output ports of the VPD/C.
One form of microwave circuit of interest herein provides for a switching of power from any one of two input ports to any one of two output ports, as well as dividing the power of either of the two input ports among the two output ports. The circuit also operates in reciprocal fashion to enable a combining of power received at the two output ports to exit one of the input ports.
An example of such a device is disclosed in the form of a rotary vane power divider in U.S. Pat. No. 5,376,905, the entirety of which is hereby incorporated by reference. The power divider disclosed in the '905 patent includes two orthomode tee to cylindrical waveguide adapters coupled by a slow-wave structure (also known as a phase shifter or delay line). The slow-wave structure is disposed between the orthomode tee adapters and includes a plurality of vanes movable to adjust their penetration through the sidewall of the waveguide section. A motor mounted to the side of the waveguide section is used to move the vanes with respect to the waveguide section.
The length and therefore the weight of such a unit is larger than desired for some applications, such as on spacecraft, where the weight and volume of equipment is preferably minimal. In addition, the weight taken up by the gearing for the side drive motor can be burdensome. An alternative to such a motor arrangement is to have a relatively complex and heavy circumference drive unit to rotate the waveguide.
Accordingly, there is a need for a small, light-weight VPD/C, to minimize or eliminate the aforementioned problems.